CONTINUOUS ETCHING SYSTEM

Abstract

The present invention relates to continuous etching system for copper etching in manufacturing of Printed Circuit Boards (PCB). The present invention more particularly relates to continuous etching system provides zero undercut, zero residue copper and non-corrosive surfaces on PCB with environmentally safe and efficient manner. The present invention provides continuous copper etching system in manufacturing of PCBs without pump or any machine force for flowing of etchant.

Claims

1. An Etching System for copper etching in manufacturing of Printed Circuit Boards (PCB) comprises a. an etching conveyer machine or chamber which comprises a plurality of conveyer rotors b. Tank(s) containing fresh Etchant set at an overhead level from the said etching machine/chamber c. Tank(s) containing spent or used etchant set at an underground level from the said etching machine/chamber d. Pipes which connect both tanks with the said etching conveyor machine/chamber e. Valves.

2. The Etching System according to claim 1, wherein the tank is made of a corrosion resistant material.

3. The Etching System according to claim 2, wherein the corrosion resistant material is PVC.

4. The Etching System according to claim 1, wherein the fresh etchant is an aqueous alkaline copper etch accelerating additive solution in the primary ammonia based copper etching solution.

5. The Etching System according to claim 1, wherein the fresh etchant is transported directly into the etching conveyor machine/chamber by gravity as the tanks are kept at an overhead level.

6. The Etching System according to claim 1, wherein the underground tank and pipe fitting attached at a level at through which the considerable spent/used etchant collected in tank.

7. The Etching System according to claim 1, wherein the tank containing the fresh etchant is connected via PVC pipes directly to the etching conveyor machine/chamber.

8. The Etching System according to claim 7, wherein the pipe is the CPVC Continuous Drip Addition pipe.

9. The Etching System according to claim 1, wherein the tank containing spent is connected via PVC pipes directly to the etching conveyor machine/chamber.

10. The Etching System according to claim 9, wherein the pipe is the Etchant Outlet pipe.

11. The Etching System according to claim 1, wherein the one on-off valve is connected at front of the CPVC Continuous Drip Addition pipe.

12. The Etching System according to claim 11, wherein control the chemical in/out from the overhead pipe to the CPVC Continuous Drip Addition pipe.

13. The Etching System according to claim 1, wherein the climatic fluid inlet valve adjacent to the one on-off valve.

14. The Etching System according to claim 13, wherein the Automatic fluid inlet valve controls the speed of chemical supplied from the overhead tank to the etch chamber.

15. The Etching System according to claim 13, wherein the Automatic fluid inlet valve controls the speed of CPVC Continuous Drip Addition pipe as per the copper thickness of the PCB being etched.

Description

DESCRIPTION OF FIGURES

[0045] FIG. 1: Layout of Conveyor Etching Machine/Chamber of the present Invention

DETAILED DESCRIPTION OF THE INVENTION

[0046] The present invention meets the above mentioned and other needs by providing continuous etching system for etching copper in manufacturing PCBs.

[0047] Now to the drawing (FIG. 1), there is shown an embodiment of a continuous etching system for etching copper in manufacturing PCBs according to the present invention.

[0048] The continuous etching system comprising a conveyer for conveying PCBs, tanks containing fresh etchant and spent, valves for controlling and adjusting continuous dripping of fresh etchant on the PCBs. The said tanks are made of a corrosion resistant material PVC.

[0049] Firstly, the continuous etching system of the present invention, the series of PVC chemical tank(s) are installed in the premise at an overhead level from the etching conveyor machine/chamber, which will contain fresh etchant. Preferably, the fresh etchant is an aqueous alkaline copper etch accelerating additive solution in the primary ammonia based copper etching solution.

[0050] The fresh etchant is stored in the overhead level tank which is connected via PVC pipes directly to the etching conveyor machine/chamber. This fresh etchant is transported directly into the etching conveyor machine/chamber by gravity as the tanks are kept at an overhead level.

[0051] Then, the series of PVC chemical tanks are installed in the premise at an underground level from the etching conveyor machine/chamber which contains spent/used etchant. The underground tank is connected via PVC pipes at such level through which the chemical automatically flows out without and pump or any machine force.

[0052] At the point where the PVC pipes from the overhead level fresh etchant tanks connected to the etching conveyor machine/chamber, a thin high profile 0.5 mm CPVC pipe is installed at the entrance of the etching conveyor machine/chamber. This pipe is carved/made of 0.5/“X” mm diameter holes at an ‘X’ distance throughout the pipe. This pipe is called the CPVC Continuous Drip Addition pipe.

[0053] One on-off valve is connected at front of the CPVC Continuous Drip Addition pipe. This valve can control the chemical etchant in/out from the overhead pipe to the CPVC Continuous Drip Addition pipe.

[0054] One Automatic fluid inlet valve is installed adjacent to the one on-oft valve for controlling the speed of chemical coming from the overhead tank to the etching conveyor machine chamber. This speed control valve can control the speed of CPVC Continuous Drip Addition pipe as per the copper thickness of the PCB being etched. The speed can be controlled as per necessary parameters of the current ongoing etching PCB. The CPVC Continuous Drip Addition pipe is kept always open/on with speed control valve only working as per PCB needs.

[0055] The etchant outlet pipe is kept at a level at the etching conveyor machine/chamber from which only the considerable or the unused or the etchant, which is not capable to etch copper anymore, flushes out of the etching bath drip by drip. This pipe is directly connected to the underground tanks installed in the premise which will only contain highly copper rich spent etchant with very minimal fresh ammonia and chloride concentrations, which can be very beneficial and easy in copper extraction process for waste management industries.

[0056] This system can automatically balance the copper density of the bath as the CPVC Continuous Drip Addition pipe continuously adds fresh etchant and the fluid overflow pipe continuously outlets spent etchant the density is optimum maintained throughout the process and through which PCB etching can be attained accurately less than 1 mil.

[0057] Due to the CPVC Continuous Drip Addition pipe, there is no issue of copper under etching problem or copper over etching problem.

[0058] This continuous etching system of the present invention overcomes all the major drawbacks arising during bare board testing process due to etching at zero stake, which can cause no rejection of PCB at final stage.

[0059] The continuous etching system of the present invention also provides solution of problem like no copper spot issue while etching process during manufacturing PCBs.

[0060] If there is no problem like under and over etching of copper during etching, sometimes there are some other problems of extra additional spots on the etched surface of the PCB which has to be removed.

[0061] On implementation of the continuous etching system of the present invention system provides permanent solution of this problem by using combination of the fresh etchant with exact chloride concentrations, exact ammonia concentrations and exact copper concentration with suitable parameter which results with no spots or under or over issue.

[0062] The continuous etching system of the present invention also eliminates ammonia smell whilst usage and feed of etching in the conveyor etching machine/chamber. As both tanks of etchant input and output of spent are connected by high quality PVC pipes. Another advantage of these pipes leads to not only protect leakage but also protect operators, workers and factory staff from irritating ammonia odor or ammonia fumes emission during etching. By this way, the continuous etching system of the present invention results in zero environment pollution which are prominent in currently used etching system.

[0063] The continuous etching system of the present invention also contributes in zero drum movement in the plant floor as the etchant is transported through fixed pipes structure which in beneficiary can make the conveyor bath surroundings and plant floor neat and clean. There is no extra drum provisions needed for emergency addition or any other activity of etchant addition, since everything is carried out automatically by gravity.

[0064] As continuous etchant is added and continuous etchant is removed in the continuous etching system of the present invention, exceptionally fast copper etching can be carried out in the conveyor bath rather than comparing a conveyor equipped with auto dosing fitted or manual feed both. Thus, the continuous etching system of the present invention leads to super-fast production speeds with far superior etching results.

[0065] In the continuous etching system of the present invention, the fresh etchant has to be emptied into the overhead level directly from the tanker and the underground etchant spent is directly filled out to the empty tanker or waste management services from the tanks installed directly out of the plant from the company premises without hampering any plant movement and causing plant production without any hindrance.

[0066] In case of Etching carried out with the auto dosing, the etching conveyor machine has to be stopped and reworked to maintain all etching optimum parameters. Then, the etching process again has to start from initial level for manufacturing PCB. Such type of re-feed and reworked many times again and again in a day. This process also becomes a headache for the etching operator as the auto dosing has to maintain all parameters like pH, density and temperature.

[0067] Through-out the continuous etching system of the present invention, all the parameters are never disturbed as the fresh etchant is continuously added by drip-by-drip and used spent etchant is continuously collected out. Moreover, the etching system of the present invention will not be stopped due to parameters remain unchanged. It is very easy to use this etchant system of the present invention for any operator as he has to just turn off the chemical inlet valve and turn off the etchant conveyor machine/chamber. When the operator will resume the work, then he can initiate the work by switching on the etchant conveyor machine/chamber without maintaining any parameters, and by turning on the fresh chemical inlet valve so that the chemical etchant starts entering through the continuous drip pipe and the process starts immediately with zero rework or re-feed with zero under etching or zero over etching. This is the main and the key benefit of this etching system of the present invention which is very necessary for all PCB manufacturers worldwide for faster and efficient etching.

[0068] This etching system of the present invention can also provide zero rejection of PCB, Zero under etching of PCB, Zero over etching of PCB, Zero production hindrance due to etching parameters, Zero drum movement on plant floor and Zero ammonia odor whilst usage.

[0069] In the above disclosure, it is understood that terms such as “a”, “an”, “the”, and like are words used for convenience and are not to be constructed as limiting terms. Although the present invention has been described in considerable detail with reference to certain preferred embodiments thereof, other versions are possible. Moreover, it will be understood that the illustrations are for the purpose describing exemplary embodiment of the invention and the same do not limit the scope of the present invention.